Sexual dimorphism represents a group of morphologic characteristics that differentiate males from females. Craniofacial morphology has inclusive particular characteristics such as dento-alveolar height, have been assessed in various ethnic groups.9–12 Other dimorphic elements have been identified relative to the mandibular bone such as the mandibular or gonial angle, the ramus length, the bigonial width, the bicondylar width. 13–16 Among these indicators, It is far observed that dimorphism is generally greater marked in mandibular ramus than in the mandibular body. Mandibular ramus can differentiate between sexes because the process of mandibular development and masticatory forces are not the same for males and females which impact the shape of the ramus. (Ayoub et al 2009, Saini et al 2011, Dong et al 2015)Mandibular ramus flexure observed by Loth and Henneberg6 has drawn international-extensive interest due to its fantastically high accuracy in sex identification. The distinct flexure in the posterior border of ramus at the level of occlusal surface of the molars in adult males is not seen in females, if present, it was either above or below the occlusal surface. The authors claimed prediction accuracy of 90.6-99% in mandibles with no loss of molar teeth. (Loth S.R and Henneberg M 1996, Saini et al 2011)
New strategies, which include medical scanning, are developed constantly, making it possible to revisit the anatomy of the mandible more effectively. At present, computerized or virtual methodologies become a developing trend in forensic anthropology, and can extend osteological assets beyond anatomic fact. The previous studies showed higher accuracy and reproducibility by computed tomography (CT) over traditional osteometry [17,18]. The introduction of Cone-Beam Computed (CBCT) era in the clinical management of patients is gaining importance due to its rapid scan time, beam limitation and improved metric accuracy with isotropic voxel resolutions. This scanning technology is advancing rapidly and is currently more cost effective, and likely to be a routine component of a dental operatory. CBCT technology has also proven valuable in volumetric analysis. So, sex determination using CBCT images seems to have some advantages compared with conventional osteometric approaches. (Angel et al 2011, Saini et al 2011, Gamba et al 2014, Dong et al 2015, Asif et al 2018)
The present study comprised of 100 living non-pathological Egyptians of 100 mandible (200 mandibular rami and angles bilaterally) — males and — females aged 20-70 years. All the patients were scanned with CBCT for various purposes using a Promax® 3DMid CBCT device (PlanmecaOy, Helsinki, Finland) in the period between 2016 and 2018.
The CBCT measurements were taken using “PlanmecaRomexis viewer R” software with the distance and angle measurement tools. Six mandibular measurements were described according to Kharoshah et al 2010. Four of them were measured from the corrected sagittal CBCT image and they are ramus angle, ramus length (Ramus-L), Minimum ramus breadth (M-Ramus-Br) and mandibular base length, i.e. gonion–gnathion length (G–G-L) as shown in Fig. 1. For The other two measurements, one was measured from the axial image which is bigonial breadth (BG-Br) and the other one was measured from the coronal image which is bicondylar breadth (BIC-Br).
The evaluators marked out the 3D locations of the three anatomical landmarks: gonion, condylion, and gnathion. The gonion is the most inferior, posterior, and lateral point on the external angle of the mandible. The condylion is the most superior and posterior point of the mandibular condyle. The gnathion is the most inferior and anterior point on the profile curvature of the chin. Then, six measurements were taken in the jaws on CBCT images according to Kharoshah et al 2010: gonial angle (GA), ramus length (RL), minimum ramus breadth (MRBr), gonionegnathion length (GGL), bicondylar breadth (BicBr) and bigonial breadth. The junction of the posterior and lower borders of the mandible forms the gonial angle. The distance between the anatomic landmarks condylion and gonion is the ramus length, the distance between the gonion and gnathion is the gonionegnathion length and the shortest width of the mandibular ramus is the minimum ramus breadth. The distance between the most lateral points on the two condyles is the bicondylar breadth. The distance between the right and left gonion is the bigonial breadth.